This invention relates to vacuum cleaners and more particularly to canister cleaners having a control for varying the negative pressure in the suction compartment.
The efficient cleaning of most off-the-floor furnishings requires a lower suction than canister cleaners are designed to supply. These cleaners are designed to provide very high suction for cleaning of carpets, and when used for cleaning of curtains, draperies or upholstery, for example, the suction at the inlet of the cleaner hose must be reduced for effective cleaning action. Most of the prior art suction reducing devices have been bleeder valves disposed on the hose wand downstream of the inlet or accessory cleaning tool. Although these generally have been effective, they lack the predictable controllability necessary for the various household cleaning chores. Some of the more recent suction reducing constructions comprise bleeder valves located in the body of the cleaner for reducing the negative pressure in the interior thereof. Examples of three of these prior art controls are illustrated in Russier, U.S. Pat. No. 3,438,081; Bell et al, U.S. Pat. No. 3,566,921 and Hohulin, U.S. Pat. No. 3,779,283. The former patent discloses a rotary valve and the latter two patents disclose push buttons for control of mechanism for varying the amount of by-pass.